The true northerner. [volume] (Paw Paw, Mich.) 1855-1920, 1887-01-26
MECHANICAL.

HOLES in stone work may be stopped
with shellac and powdered stone. Beat
up some of the same kind of stone you
wish to fill up to q fine powder, mix
it with the shellac; before filling brush
the holes out with liquid shellac; fill
the holes little more than even or
flush with the surface, so as to leave
some to be rubbed off; it is always
better to have them too full than not full
enough.
A FRENCH architectural journal re-
calls an observation made by Violet
le-Duc that lead plates for roofing pur-
poses are often pierced by insects. He
accuses the wasps of being the authors
of the little holes that he found gnawed
in lead roofs, but later observers have
discovered that both worms and flies
often drill through heavy plates.
Twenty-Five years ago it was found
that the lead bullets of cartridges that
had been stored in wooden boxes were
badly gnawed, and q number of gall
or saw flies were found in the act of
working upon them.
The smallest oscillating engine in
the world has been made by John II.
Hare, OF Baltimore. 1t is about half
as big as a collar button, and is hidden
completely beneath a chlld's thimble.
Its bore is one-siXteenth of an inch.
and the stroke one-eighth. The wheel,
shaft and crank weigh eight grains,
the cylinder five, and the stand and
pillar twelve grains, making the whole
weight one pennyweight one grain.
Run by compressed air, 1T makes three
thousand revolutions a minute. Mr..
Hare has also made an engine which is
covered with an English walnut shell.
A NEW method of manufacturing car
wheels has been tested at Wilkesbarre,
Pa, with satisfactory results. BY the
old method three men could make only
eighteen wheels per day of twelve
hours. By the new process the same
number of men can turn out perfect
wheel every minute, or 720 per day.
One of the principal features of the
new method is the use OF steel core
instead of one of sand in casting the
wheel. The core is removed by knock
ing out the center key, leaving the hole
perfectly true, and ready to be put upon
the axle at once, without dressing or
boring.
ACCORDING to the opinion commonly
entertained, the draught in chimneys is
reduced by sunshine, and the rays of
the sun exert, as it were, q backward
pressure on the smoke. Since Prof.
Crooke's discovery of the mechanical
work done by light, there seemed to be
a chance of this view being correct
l. 8 g,,I
experiments, Hohlrausch has come to
the conclusion that the rays of the sun
do not press back the smoke. 1t is re-
garded as probable that the draught in
chimneys is influenced by sunshine
upon it in the following way: The air
around the chimney being heated to a
greater or less degree, the difference of
the temperature inside and outside of
the chimney, and consequently the
draught, is reduced.
TIE abundance of salt formations in
Nevada is illustrated in the fact that
in Lincoln County there is a deposit of
pure rock salt which is exposed for a
length of two miles, width of half q
mile, and is of unknown depth; in
places canyons are cut through it to q
depth of sixty feet, and not only has
the deposit been traced on the surface
for a distance of nine miles, but it is so
solid in places as to require blasting
like rock, and so pure and transparent
that print can be read through blocks
of it some inches thick. In Churchill
County there is said to be deposit of
rock salt some fourteen feet in depth,
free from any particle of foreign sub
stance, and which can be quarried at
the rate of five tons day to a man.
What is known as the great Humboldt
salt field is estimated to be some fifteen
miles long by six wide. According to
the description, when the summer heats
have evaporated the surface water, salt
to the depth of several inches may be
scraped up, and underneath there is q
stratum of rock salt of the purest de-
scription, and of depth unknown.